iio: imu: st_lsm6dsx: flush hw FIFO before resetting the device

flush hw FIFO before device reset in order to avoid possible races
on interrupt line 1. If the first interrupt line is asserted during
hw reset the device will work in I3C-only mode (if it is supported)

Fixes: 801a6e0a ("iio: imu: st_lsm6dsx: add support to LSM6DSO")
Fixes: 43901008 ("iio: imu: st_lsm6dsx: add support to LSM6DSR")
Reported-by: Mario Tesi <mario.tesi@st.com>
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Reviewed-by: Vitor Soares <vitor.soares@synopsys.com>
Tested-by: Vitor Soares <vitor.soares@synopsys.com>
Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_core.c

@@ -2036,11 +2036,21 @@ static int st_lsm6dsx_init_hw_timer(struct st_lsm6dsx_hw *hw)
 	return 0;
 }
 
-static int st_lsm6dsx_init_device(struct st_lsm6dsx_hw *hw)
+static int st_lsm6dsx_reset_device(struct st_lsm6dsx_hw *hw)
 {
 	const struct st_lsm6dsx_reg *reg;
 	int err;
 
+	/*
+	 * flush hw FIFO before device reset in order to avoid
+	 * possible races on interrupt line 1. If the first interrupt
+	 * line is asserted during hw reset the device will work in
+	 * I3C-only mode (if it is supported)
+	 */
+	err = st_lsm6dsx_flush_fifo(hw);
+	if (err < 0 && err != -ENOTSUPP)
+		return err;
+
 	/* device sw reset */
 	reg = &hw->settings->reset;
 	err = regmap_update_bits(hw->regmap, reg->addr, reg->mask,
@@ -2059,6 +2069,18 @@ static int st_lsm6dsx_init_device(struct st_lsm6dsx_hw *hw)
 
 	msleep(50);
 
+	return 0;
+}
+
+static int st_lsm6dsx_init_device(struct st_lsm6dsx_hw *hw)
+{
+	const struct st_lsm6dsx_reg *reg;
+	int err;
+
+	err = st_lsm6dsx_reset_device(hw);
+	if (err < 0)
+		return err;
+
 	/* enable Block Data Update */
 	reg = &hw->settings->bdu;
 	err = regmap_update_bits(hw->regmap, reg->addr, reg->mask,